Unveiling Versatile Electronic Properties and Contact Features of Metal-Semiconductor Graphene/γ-Ge2SSe van der Waals Heterostructures.

Recently, searching for a metal-semiconductor junction (MSJ) that exhibits low-contact resistance has received tremendous consideration, as they are essential components in next-generation field-effect transistors. In this work, we design a MSJ by integrating two-dimensional (2D) graphene as the metallic electrode and 2D Janus γ-Ge2SSe as the semiconducting channel using first-principles simulations. All the graphene/γ-Ge2SSe MSJs are predicted to be energetically, mechanically, and thermodynamically stable, characterized by the weak van der Waals (vdW) interactions. The graphene/γ-SGe2Se MSJ-vdWH form the n-type Schottky contact (SC), while the graphene/γ-SeGe2S MSJ-vdWH form the p-type one, suggesting that the switching between p-type and n-type SC in the graphene/γ-Ge2SSe MSJ-vdWHs can occur spontaneously by simply altering the stacking patterns, without requiring any external conditions. Notably, the contact features, including contact types and barriers of the graphene/γ-Ge2SSe MSJs are significant in versatility and can be altered by applying electric gating and adjusting interlayer spacing. Both the applied electric gating and strain engineering induce switchability between p- and n-type and SC to OC in the graphene/γ-Ge2SSE MSJs. This versatility underscores the potential of the graphene/γ-Ge2SSe MSJ for next-generation applications that require low-contact resistance and high performance.

Tunable Electronic Properties, Carrier Mobility, and Contact Characteristics in Type-II BSe/Sc2CF2 Heterostructures toward Next-Generation Optoelectronic Devices.

Conducting heterostructures have emerged as a promising strategy to enhance physical properties and unlock the potential application of such materials. Herein, we conduct and investigate the electronic and transport properties of the BSe/Sc2CF2 heterostructure using first-principles calculations. The BSe/Sc2CF2 heterostructure is structurally and thermodynamically stable, indicating that it can be feasible for further experiments. The BSe/Sc2CF2 heterostructure exhibits a semiconducting behavior with an indirect band gap and possesses type-II band alignment. This unique alignment promotes efficient charge separation, making it highly promising for device applications, including solar cells and photodetectors. Furthermore, type-II band alignment in the BSe/Sc2CF2 heterostructure leads to a reduced band gap compared to the individual BSe and Sc2CF2 monolayers, leading to enhanced charge carrier mobility and light absorption. Additionally, the generation of the BSe/Sc2CF2 heterostructure enhances the transport properties of the BSe and Sc2CF2 monolayers. The electric fields and strains can modify the electronic properties, thus expanding the potential application possibilities. Both the electric fields and strains can tune the band gap and lead to the type-II to type-I conversion in the BSe/Sc2CF2 heterostructure. These findings shed light on the versatile nature of the BSe/Sc2CF2 heterostructure and its potential for advanced nanoelectronic and optoelectronic devices.

Understanding Electronic Properties and Tunable Schottky Barriers in a Graphene/Boron Selenide van der Waals Heterostructure.

van der Waals heterostructures provide a powerful platform for engineering the electronic properties and for exploring exotic physical phenomena of two-dimensional materials. Here, we construct a graphene/BSe heterostructure and examine its electronic characteristics and the tunability of contact types under electric fields. Our results reveal that the graphene/BSe heterostructure is energetically, mechanically, and thermodynamically stable at room temperature. It forms a p-type Schottky contact and exhibits a high carrier mobility, making it a promising candidate for future Schottky field-effect transistors. Furthermore, applying an electric field not only reduces contact barriers but also induces a transition from a p-type to an n-type Schottky contact and from a Schottky to an ohmic contact, offering further potential for the control and manipulation of the heterostructure's electronic properties. Our findings offer a rational basis for the design of energy-efficient and tunable heterostructure devices based on the graphene/BSe heterostructure.

On the impact of adsorbed gas molecules on the anisotropic electro-optical properties of ß12-borophene.

We theoretically study the role of adsorbed gas molecules on the electronic and optical properties of monolayer ß12-borophene with {a,b,c,d,e} atoms in its unit cell. We focus our attention on molecules NH3, NO, NO2, and CO, which provide additional states permitted by the host electrons. Utilizing the six-band tight-binding model based on an inversion symmetry (between {a,e} and {b,d} atoms) and the Kubo formalism, we survey the anisotropic electronic dispersion and the optical multi-interband spectrum produced by molecule-boron coupling. We consider the highest possibilities for the position of molecules on the boron atoms. For molecules on {a,e} atoms, the inherent metallic phase of ß12-borophene becomes electron-doped semiconducting, while for molecules on {b,d} and c atoms, the metallic phase remains unchanged. For molecules on {a,e} and {b,d} atoms, we observe a redshift (blueshift) optical spectrum for longitudinal/transverse (Hall) component, while for molecules on c atoms, we find a redshift (blueshift) optical spectrum for longitudinal (transverse/Hall) component. We expect that this study provides useful information for engineering field-effect transistor-based gas sensors.

Evaluating M2BPGi as a Marker for Liver Fibrosis in Patients with Chronic Hepatitis B.

BACKGROUND: The accurate evaluation of liver fibrosis is crucial for the treatment and follow up of chronic hepatitis B (CHB) patients. AIM: We examined the efficiency of serum Mac-2 Binding Protein Glycosylation isomer (M2BPGi) in diagnosing liver fibrosis stages in CHB patients. METHODS: A cross-sectional study was conducted on 177 adult CHB patients visiting the University Medical Center Ho Chi Minh City, Vietnam between October 2019 and December 2021. M2BPGi, ARFI, APRI, and FIB-4 were tested against FibroScan® for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The optimal M2BPGi cut-off values were identified based on the area under the receiver operating characteristic (AUROC) curve. RESULTS: There was a strong agreement between M2BPGi and FibroScan® (r = 0.77, P < 0.001). The optimal M2BPGi cut-off index (C.O.I) for detecting significant fibrosis (F ≥ 2) was 0.79 with an AUROC of 0.77, 67.3% sensitivity, 70% specificity, 60.6% NPV, and 75.3% PPV. Compared with APRI (61%) and FIB-4 (47%), M2BPGi had the greatest sensitivity for diagnosing F ≥ 2. M2BPGi combined with APRI yielded highest diagnosis performance for F ≥ 2 with an AUROC of 0.87. The optimal cut-off index of M2BPGi for diagnosing cirrhosis (F4) was 1.3 with an AUROC of 0.91, 88% sensitivity, 87.4% specificity, 97% NPV, and 61% PPV. The AUROC of M2BPGi for diagnosing F4 was comparable to that of ARFI (0.93). CONCLUSIONS: With cut-off values of 0.79 C.O.I and 1.3 C.O.I, M2BPGi could be an effective method for diagnosing significant fibrosis and cirrhosis in CHB patients, respectively.

Tunability of the electronic properties and electrical contact in graphene/SiH heterostructures.

Stacking different two-dimensional materials to generate a vertical heterostructure has been considered a promising way to obtain the desired properties and improve device performance. Here, in this work, using first principles calculations, we design a vertical heterostructure by stacking graphene (GR) and silicane (SiH) and investigate the electronic properties and electrical contact in the GR/SiH heterostructure as well as the possibility of tuning these properties under an external electric field and vertical strain. The GR/SiH heterostructure is structurally and mechanically stable at the equilibrium interlayer separation. The GR/SiH heterostructure exhibits a p-type Schottky contact with a small Schottky barrier of 0.43 eV, presenting great tunability of the electrical contact from Schottky to Ohmic contact under different conditions. The external electric field not only leads to a transition from the p-type to n-type Schottky contact but also induces a transformation from a Schottky contact to Ohmic one. Furthermore, changing the interlayer separation can be considered a useful tool to regulate the Schottky barriers and electric contact in the GR/SiH heterostructure, which is prominent for constructing electronic devices. Our findings could provide an effective tool for the design of high-performance nanoelectronic devices based on the GR/SiH heterostructure.

Rashba-type spin splitting and transport properties of novel Janus XWGeN2 (X = O, S, Se, Te) monolayers.

We discuss and examine the stability, electronic properties, and transport characteristics of asymmetric monolayers XWGeN2 (X = O, S, Se, Te) using ab initio density functional theory. All four monolayers of quintuple-layer atomic Janus XWGeN2 are predicted to be stable and they are all indirect semiconductors in the ground state. When the spin-orbit coupling (SOC) is included, a large spin splitting at the K point is found in XWGeN2 monolayers, particularly, a giant Rashba-type spin splitting is observed around the Γ point in three structures SWGeN2, SeWGeN2, and TeWGeN2. The Rashba parameters in these structures are directionally isotropic along the high-symmetry directions Γ-K and Γ-M and the Rashba constant αR increases as the X element moves from S to Te. TeWGeN2 has the largest Rashba energy up to 37.4 meV (36.6 meV) in the Γ-K (Γ-M) direction. Via the deformation potential method, we calculate the carrier mobility of all four XWGeN2 monolayers. It is found that the electron mobilities of OWGeN2 and SWGeN2 monolayers exceed 200 cm2 V-1 s-1, which are suitable for applications in nanoelectronic devices.

Bony Cartilaginous Graft in Unilateral Cleft Lip Rhinoplasty.

BACKGROUND: Cleft rhinoplasty is a challenging form of nasal correction of both esthetic and functional deformities. The septal cartilage in many Asian patients are not sufficient and weak. Does a combination of the septal cartilage and the bony septum have both esthetic and functional benefits to secondary unilateral cleft rhinoplasty? PATIENTS AND METHODS: Thirty patients with a unilateral cleft lip palate underwent open rhinoplasty from October 2018 to January 2021. After preserving a 10 mm L-strut, the posterior cartilaginous and bony septum were harvested as an integrative unit. The osteocartilaginous graft was used as a caudal septal extension graft and an extended spreader graft. Correcting the asymmetry of the tip and tip projection followed. The intraoperative harvested composite graft was analyzed. Acoustic rhinometry and the 3-dimensional anthropometric measurements of the external nose were assessed before and after surgery. RESULTS: The osteocartilaginous unit was much larger than the cartilaginous part of this unit. The mean nasal tip height and the nasolabial angle increased significantly after surgery. The measurement of cross-sectional areas and volumes by acoustic rhinometry revealed that septorhinoplasty provided a significant increase in the function of both nasal cavities. CONCLUSIONS: This septal bony cartilaginous graft is effective for cleft lip nasal deformity when correcting the deviated septum, creating a supporting frame to correct the nasal tip asymmetry, improving function.

Biological Activities of Lichen-Derived Monoaromatic Compounds.

Lichen-derived monoaromatic compounds are bioactive compounds, associated with various pharmacological properties: antioxidant, antifungal, antiviral, cytotoxicity, and enzyme inhibition. However, little is known about data regarding alpha-glucosidase inhibition and antimicrobial activity. Very few compounds were reported to have these activities. In this paper, a series of monoaromatic compounds from a lichen source were isolated and structurally elucidated. They are 3,5-dihydroxybenzoic acid (1), 3,5-dihydroxybenzoate methyl (2), 3,5-dihydroxy-4-methylbenzoic acid (3), 3,5-dihydroxy-4-methoxylbenzoic acid (4), 3-hydroxyorcinol (5), atranol (6), and methyl hematommate (7). To obtain more derivatives, available compounds from the previous reports such as methyl ß-orsellinate (8), methyl orsellinate (9), and D-montagnetol (10) were selected for bromination. Electrophilic bromination was applied to 8-10 using NaBr/H2O2 reagents to yield products methyl 5-bromo-ß-orsellinate (8a), methyl 3,5-dibromo-orsellinate (9a), 3-bromo-D-montagnetol (10a), and 3,5-dibromo-D-montagnetol (10b). Compounds were evaluated for alpha-glucosidase inhibition and antimicrobial activity against antibiotic-resistant, pathogenic bacteria Enterococcus faecium, Staphylococcus aureus, and Acinetobacter baumannii. Compound 4 showed stronger alpha-glucosidase inhibition than others with an IC50 value of 24.0 µg/mL. Synthetic compound 9a exhibited remarkable activity against Staphylococcus aureus with a MIC value of 4 µg/mL. Molecular docking studies were performed to confirm the consistency between in vitro and in silico studies.

α-Glucosidase Inhibitory and Antimicrobial Benzoylphloroglucinols from Garcinia schomburgakiana Fruits: In Vitro and In Silico Studies.

α-Glucosidase plays a role in hydrolyzing complex carbohydrates into glucose, which is easily absorbed, causing postprandial hyperglycemia. Inhibition of α-glucosidase is therefore an ideal approach to preventing this condition. A novel polyprenylated benzoylphloroglucinol, which we named schomburgkianone I (1), was isolated from the fruit of Garcinia schomburgkiana, along with an already-reported compound, guttiferone K (2). The structures of the two compounds were determined using NMR and HRESIMS analysis, and comparisons were made with previous studies. Compounds 1 and 2 exhibited potent α-glucosidase inhibition (IC50s of 21.2 and 34.8 µM, respectively), outperforming the acarbose positive control. Compound 1 produced wide zones of inhibition against Staphylococcus aureus and Enterococcus faecium (of 21 and 20 mm, respectively), compared with the 19 and 20 mm zones of compound 2, at a concentration of 50 µg/mL. The MIC value of compound 1 against S. aureus was 13.32 µM. An in silico molecular docking model suggested that both compounds are potent inhibitors of enzyme α-glucosidase and are therefore leading candidates as therapies for diabetes mellitus.

Delineating the role of cooperativity in the design of potent PROTACs for BTK.

Proteolysis targeting chimeras (PROTACs) are heterobifunctional small molecules that simultaneously bind to a target protein and an E3 ligase, thereby leading to ubiquitination and subsequent degradation of the target. They present an exciting opportunity to modulate proteins in a manner independent of enzymatic or signaling activity. As such, they have recently emerged as an attractive mechanism to explore previously "undruggable" targets. Despite this interest, fundamental questions remain regarding the parameters most critical for achieving potency and selectivity. Here we employ a series of biochemical and cellular techniques to investigate requirements for efficient knockdown of Bruton's tyrosine kinase (BTK), a nonreceptor tyrosine kinase essential for B cell maturation. Members of an 11-compound PROTAC library were investigated for their ability to form binary and ternary complexes with BTK and cereblon (CRBN, an E3 ligase component). Results were extended to measure effects on BTK-CRBN cooperative interactions as well as in vitro and in vivo BTK degradation. Our data show that alleviation of steric clashes between BTK and CRBN by modulating PROTAC linker length within this chemical series allows potent BTK degradation in the absence of thermodynamic cooperativity.

Identification of Highly Potent α-Glucosidase Inhibitors from Artocarpus integer and Molecular Docking Studies.

A new natural Diels-Alder adduct (3) was isolated from the leaves and stem bark of Artocarpus integer, along with seventeen known compounds (1, 2, and 4-18). Structural elucidation was conducted using NMR and HR-ESI-MS data, and comparisons were made with previous studies. Deoxyartonin I (3) exhibited the most potent α-glucosidase inhibition (IC50 7.80±0.1 µM), outperforming the acarbose positive control. This was mixed-mode inhibition, as indicated by the intersect in the second quadrant of each respective plot. An in silico molecular docking model and the pharmacokinetic features of 3 suggest that it is a potential inhibitor of enzyme α-glucosidase, and is therefore a lead candidate as a drug against diabetes mellitus.

Flavones from Combretum quadrangulare Growing in Vietnam and Their Alpha-Glucosidase Inhibitory Activity.

Combretum quadrangulare Kurz is widely used in folk medicine in Eastern Asia and is associated with various ethnopharmacological properties including hepatoprotective, antipyretic, analgesic, antidysenteric, and anthelmintic activities. Previous phytochemical investigations reported the presence of numerous triterpenes (mostly cycloartanes, ursanes, lupanes, and oleananes) along with dozens of flavonoids. However, the extracts of C. quadrangulare and isolated flavonoids have not been evaluated for their alpha-glucosidase inhibition. In the frame of our efforts dedicated to the chemical investigation of Vietnamese medicinal plants and their biological activities, a phytochemical study of the MeOH extract of the leaves of C. quadrangulare using bioactive guided isolation was undertaken. In this paper, the isolation and structure elucidation of twelve known compounds, 5-hydroxy-3,7,4'-trimethoxyflavone (1), ayanin (2), kumatakenin (3), rhamnocitrin (4), ombuin (5), myricetin-3,7,3',5'-tetramethyl ether (6), gardenin D (7), luteolin (12), apigenin (13), mearnsetin (14), isoorientin (15), and vitexin (16) were reported. Bromination was applied to compounds 2 and 3 to provide four new synthetic analogues 8-11. All isolated and synthesized compounds were evaluated for alpha-glucosidase inhibition and antibacterial activity. Compounds 4 and 5 showed moderate antibacterial activity against methicillin-resistant Staphylococcus aureus while others were inactive. All compounds failed to reveal any activity toward extended spectrum beta-lactamase-producing Escherichia coli. Compounds 2, 4, 6-9, and 11-14 showed good alpha-glucosidase inhibition with IC50 values in the range of 30.5-282.0 µM. The kinetic of enzyme inhibition showed that 8 and 11 were noncompetitive type inhibition against alpha-glucosidase. In silico molecular docking model indicated that compounds 8 and 11 were potential inhibitors against enzyme α-glucosidase.

Physicochemical properties of L- and DL-valine: first-principles calculations.

At present, physicochemical properties of amino acid molecular crystals are of the utmost interest. The compounds where molecules have different chirality are the focus of particular interest. This paper, presents a study on the structural and electronic properties of crystalline L- and DL-valine within the framework of density functional theory including van der Waals interactions. The results of this study showed that electronic properties of the two forms of valine are similar at zero pressure. Pressure leads to different responses in these crystals which is manifested as various deformations of molecules. The pressure effect on the infrared spectra and distribution of electron density of L- and DL-valine has been studied.

Microbiome-skin-brain axis: A novel paradigm for cutaneous wounds.

Chronic wounds cause a significant burden on society financially, medically, and psychologically. Unfortunately, patients with nonhealing wounds often suffer from comorbidities that further compound their disability. Given the high rate of depressive symptoms experienced by patients with chronic wounds, further studies are needed to investigate the potentially linked pathophysiological changes in wounds and depression in order to improve patient care. The English literature on wound healing, inflammatory and microbial changes in chronic wounds and depression, and antiinflammatory and probiotic therapy was reviewed on PubMed. Chronic wound conditions and depression were demonstrated to share common pathologic features of dysregulated inflammation and altered microbiome, indicating a possible relationship. Furthermore, alternative treatment strategies such as immune-targeted and probiotic therapy showed promising potential by addressing both pathophysiological pathways. However, many existing studies are limited to a small study population, a cross-sectional design that does not establish temporality, or a wide range of confounding variables in the context of a highly complex and multifactorial disease process. Therefore, additional preclinical studies in suitable wound models, as well as larger clinical cohort studies and trials are necessary to elucidate the relationship between wound microbiome, healing, and depression, and ultimately guide the most effective therapeutic and management plan for chronic wound patients.

Tunable electronic properties of the dynamically stable layered mineral Pt2HgSe3 (Jacutingaite).

Density functional theory calculations are performed in order to study the structural and electronic properties of monolayer Pt2HgSe3. Our results show that the dynamically stable monolayer Pt2HgSe3 is a topological insulator with a band gap of 160 meV. In addition, the effect of layer thickness, strain and electric field on the electronic properties are systematically investigated using fully relativistic calculations. We find that the electronic properties are sensitive to the applied electric field. With increasing electric field strength up to 0.5 V Å-1, the band gap decreases from 160 to 10 meV at 0.5 V Å-1. Interestingly, upon further increasing the electric field up to 1.0 V Å-1, the band gap opens again and reaches its bare value (160 meV) at 1.0 V Å-1, which indicates that the band gap is reversibly controllable via the applied external electric field. Moreover, the electronic properties are also examined under uniaxial and biaxial strain. Our results reveal that the band gap value can be tuned to 150 meV (at 1%) and to 92 meV (at 6%) under uniaxial strain, while under biaxial tensile strain, it increases to 170 meV at 5% and fluctuates between 150 and 100 meV in the range of 5-10%. In contrast, the biaxial-compressive strain is found to drive the semiconducting-to-metallic transition for sufficiently large compressions (over 8%). On the other hand, we find that increasing the thickness of Pt2HgSe3 modifies the band gap to 150 meV (for the bilayer) and 140 meV (for the trilayer). In the bilayer Pt2HgSe3 structure, we further investigated the effect of out-of-plane pressure, both compressive and tensile, and our results show that the electronic structure of bilayer Pt2HgSe3 is largely preserved. Our study provides new insight into the modification of the electronic structure of monolayer Pt2HgSe3 upon application of external fields and variation in the layer thickness.

van der Waals heterostructures based on MSSe (M = Mo, W) and graphene-like GaN: enhanced optoelectronic and photocatalytic properties for water splitting.

The geometric structure, electronic, optical and photocatalytic properties of MSSe-g-GaN (M = Mo, W) van der Waals (vdW) heterostructures are investigated by performing first-principles calculations. We find that the MoSSe-g-GaN heterostructure exhibits type-II band alignment for all stacking patterns. While the WSSe-g-GaN heterostructure forms the type-II or type-I band alignment for the stacking model-I or model II, respectively. The average electrostatic potential shows that the potential of g-GaN is deeper than the MSSe monolayer, leading to the formation of an electrostatic field across the interface, causing the transfer of photogenerated electrons and holes. Efficient interfacial formation of interface and charge transfer reduce the work function of MSSe-g-GaN vdW heterostructures as compared to the constituent monolayer. The difference in the carrier mobility for electrons and holes suggests that these heterostructures could be utilized for hole/electron separation. Absorption spectra demonstrate that strong absorption from infrared to visible light in these vdW heterostructures can be achieved. Appropriate valence and conduction band edge positions with standard redox potentials provide enough force to drive the photogenerated electrons and holes to dissociate water into H+/H2 and O2/H2O at pH = 0.

Stark and Zeeman effects on the topological phase and transport properties of topological crystalline insulator thin films.

The fundamental investigation of topological crystalline insulator (TCI) thin films is essential for observing interesting phenomena. In practice, a promising pathway involves the application of electric and magnetic fields to tune the topological phases of TCI thin films. To achieve this, we applied a perpendicular electric field and an in-plane magnetic field to not only tune the Dirac gap of a SnTe(001) thin film and find the phase transition but also to directly connect them with their effects on the group velocity of both massless and massive surface Dirac fermions. The TCI thin film is an inherent insulator due to the hybridization between the front and back surfaces, and it transitions to a semimetal phase at a critical perpendicular electric field due to the Stark effect. Correspondingly, the anisotropic group velocity of the upper (lower) conduction (valence) band decreases (increases) with the electric field at certain momenta. We found that when one of the in-plane Zeeman field components becomes stronger than the intrinsic hybridization potential, the anisotropic Weyl cones with opposite chiralities retrieve at the critical momenta and the corresponding group velocities become zero. Further, the isotropic in-plane Zeeman field leads to rotation of the band structure, as expected, resulting in non-zero group velocities along all directions. Finally, for the sake of completeness, the combined Stark and Zeeman effects are tracked and the results show that the system is an insulator at all fields and the group velocities are altered more than when the individual Stark and Zeeman effects are applied. Our findings may provide interesting physical insights for practical applications in nanoelectronics and spintronics.

Electronic properties and enhanced photocatalytic performance of van der Waals heterostructures of ZnO and Janus transition metal dichalcogenides.

Vertical stacking of two-dimensional materials into layered van der Waals heterostructures has recently been considered as a promising candidate for photocatalytic and optoelectronic devices because it can combine the advantages of the individual 2D materials. Janus transition metal dichalcogenides (JTMDCs) have emerged as an appealing photocatalytic material due to the desirable electronic properties. Hence, in this work, we systematically investigate the geometric features, electronic properties, charge density difference, work function, band alignment and photocatalytic properties of ZnO-JTMDC heterostructures using first-principles calculations. Due to the different kinds of chalcogen atoms on both sides of JTMDC monolayers, two different possible stacking patterns of ZnO-JTMDC heterostructures have been constructed and considered. We find that all these stacking patterns of ZnO-JTMDC heterostructures are dynamically and energetically feasible. Moreover, both ZnO-MoSSe and ZnO-WSSe heterostructures are indirect band gap semiconductors and present type-I and type-II band alignments for model-I and model-II, respectively. The Rashba spin polarization of the ZnO-WSSe heterostructure for model-I is greater than that in the others. Furthermore, valence (conduction) band edge potentials are calculated to understand the photocatalytic behavior of these systems. Energetically favorable band edge positions in ZnO-Janus heterostructures make them suitable for water splitting at zero pH. We found that the ZnO-Janus heterostructures are promising candidates for water splitting with conduction and valence band edges positioned just outside of the redox interval.

Effects of different surface functionalization on the electronic properties and contact types of graphene/functionalized-GeC van der Waals heterostructures.

Constructing vertical heterostructures by placing graphene (Gr) on two-dimensional materials has recently emerged as an effective way to enhance the performance of nanoelectronic and optoelectronic devices. In this work, first principles calculations are employed to explore the structural and electronic properties of Gr/GeC and Gr/functionalized-GeC by H/F/Cl surface functionalization. Our results imply that the electronic properties of the Gr, GeC and all functionalized-GeC monolayers are well preserved in Gr/GeC and Gr/functionalized-GeC heterostructures, and the Gr/GeC heterostructure forms a p-type Schottky contact. Interestingly, we find that the p-type Schottky contact in Gr/GeC can be converted into the n-type one and into an n-type ohmic contact by H/F/Cl surface functionalization to form Gr/functionalized-GeC heterostructures. Furthermore, we find that electric fields and strain engineering can change both the Schottky barrier heights and the contact types of the Gr/functionalized-GeC vdWHs. These findings suggest that Gr/functionalized-GeC heterostructures can be considered as a promising candidate for designing high-performance optoelectronic and nanoelectronic devices.